If you have a fully updated version of the game client and it crashes with or without an error report and have an antivirus running it is possible that the crash error is the security program not recognizing the RO client when it tries to connect to the internet. This is most common after a major update, where we change the client .exe file.
Instructions for Avast
1. Right click the Avast icon and open the Avast program.
2. Click Real-Time Shields
3. Click Expert settings
4. Trusted Processes
5. Click the empty line then click browse and navigate to the Ragnarok folder on your harddrive
(this is usually: Local Disk C: \Program Files\Gravity\RagnarokOnline
6. choose clragexe and ragexe to add to the trusted processes list, if possible add the entire RO folder to be exempted.
For other antivirus programs
You will need to find Trusted Processes or under Manage Exceptions to add both Ragnarok clients to the safe list. Please make sure to right click on the game client and choose "run as administrator" when you patch for the first time.